Known in the art is a two-platen type clamping device which executes mold thickness (die height) adjustment at each molding cycle (for example Patent Literature 1 or Patent Literature 2). For example, the clamping device in Patent Literature 1 has a fixed die plate which holds a fixed mold, a movable die plate which holds a movable mold and can move in a mold opening and closing direction, clamping pistons which are built in the fixed die plate, tie bars which are fixed at single ends to the clamping pistons and have male screw-shaped engaged parts at the other ends, and a split nut devices which are connected to the movable die plate and can be engaged/disengaged with respect to the engaged parts of the tie bars. This clamping device, in the molding cycle, first, moves the movable die plate to the fixed die plate side (mold closing direction) to close the molds. At this time, the split nut devices move relative to the tie bars, and then the split nut devices and the engaged parts of the tie bars are relatively positioned in accordance with the mold thickness. Next, the clamping pistons are driven to enable the split nut devices and the engaged parts to mesh with each other by adjusting the positions of the tie bars by a distance of less than 1 pitch of the thread grooves (the mold thickness adjustment is executed). After that, the split nut devices and the engaged parts are meshed with each other and the clamping pistons are driven, whereby the tie bars are extended and molds are clamped.
In Patent Literature 3, stoppers are provided in order to stabilize the mold thickness adjustment at each molding cycle described above. Specifically, the clamping device in Patent Literature 3 has a fixed die plate which holds a fixed mold, a movable die plate which holds a movable mold and can move in a mold opening and closing direction, clamping pistons which are built in the fixed die plate, tie bars which are connected at single ends to the movable die plate and have male screw-shaped engaged parts at the other ends, and split nut devices which are connected to the clamping pistons and can be engaged/disengaged with respect to the engaged parts of the tie bars. In this clamping device, along with the movement of the movable die plate, the tie bars (engaged parts) move relative to the clamping pistons and split nut devices. The stoppers are adjusted in advance before the molding cycle at positions in accordance with the mold thickness and abut against the clamping pistons so as to position the clamping pistons at positions where the engaged parts and the split nut devices can mesh with each other. Due to this, the relative positions of the split nut devices and the engaged parts when making them mesh with each other are stabilized. Note that, this abutting action is carried out from the sides opposite to the movement directions of the clamping pistons at the time of clamping.
In Patent Literature 3, a plurality of the stoppers are provided corresponding to the plurality of tie bars. The plurality of stoppers are driven in the mold opening and closing direction by transmission of driving force of one stepping motor through a chain to the plurality of stoppers.